Transcript Document

Nanophysics with Ion Beams
Peter Lieb, University of Göttingen
Lectures on 22.-27.04.09 @ VINCA
Epitaxy and luminescence
of ion-irradiated quartz
Ion implantation in ferromagnetic layers
Hyperfine interactions of implanted tracers
using perturbed angular correlations
EPITAXY & LUMINESCENCE AFTER
ION IMPLANTATION IN -QUARTZ
W.Bolse, S.Dhar,
S.Gasiorek, J.Keinonen,
K.P.Lieb, F.Roccaforte,
P.K.Sahoo, T.Sajavaara
University of Göttingen
University of Helsinki
Supported by DFG, DAAD
& Academy of Finland
Tetrahedrite & Quartz from Trepca,
10 km east of Kosozska-Mitrovica
1. Introduction
2. Epitaxy of quartz after ion irradiation
3. Luminescence and defects
4. New directions
1. Introduction
 Hexagonal
latticeFirst
structure
Intel Builds
Successful Photonic
3  silica: 2.35 g/cm3
Computer
Density of quartz:
2.65 g/cm
Processor,
Uses
Quartz Crystals
September
2006
 Melting point =18.
1710C
@ normal
pressure

large
= 8 eV!
TheVery
hybrid
chipband
used gap
36 lasers
on one die that used 36 modulators
and a multiplexor
route and
light UV
beams with varying waveTransparent
in theto
visible
lengths through optical fiber. Each laser is about 1 m wide and
800Introduce
color compares
centers by
implantation
m long, which
to ion
the width
of a human hair of
(impurity
& intrinsic
& nanoparticles)
about
100 m.
Down thedefects
road, Intel
aims to combine the
platform with a data receiver chip to build an integrated silicon photonic chip. The chip, currently considered part of Intel's
"TeraScale" program to build processors with "10-00s" of cores,
then would be built into computer boards and serve as
interconnect between busses, between PCs and networks.
The actual performance capability of such devices are still to
be seen, but Intel claims that 25 hybrid silicon lasers on a chip,
would provide the aggregate band-width of 1 Terabit (25 x 40
Gb/s). Intel did not specify when such silicon laser chips would
actually be available. However, with the claim that the "last
major hurdle" is taken, Intel appears to be well on track to ...
introduce the first photonic chips "by the end of the decade."
www.tgdaily.com Copyright by TG Daily
10. April 2009
Collision cascade 175 keV Ba+ a-SiO2 (SRIM 2000)
.
1 Ba+-ion
Ba-range distribution
mean range = 80 nm
10 ions
 Each ion produces its
own collision cascade
with regions of high and
low damage density
 Cascades of individual
ions are well separated
in time
 Damage distribution
peaks closer to surface
than range distribution
Harbsmeier & Bolse
1000 ions
0
Depth x (nm)
200
0
Depth x (nm)
200
 Critical energy for amorphization is only 2 eV/at
 For low fluences: defect
agglomeration & small
amorphous zones embedded in crystalline matrix
 For high fluences: continuous amorphous layer
Epitaxy of Quartz. Goal & Experiments
Epitaxy of quartz after or during ion irradiation
Dynamic Epitaxy
Laser Epitaxy
=
Implantation into hot quartz
=
Epitaxy after ion implantation
with pulsed excimer laser
Chemical Epitaxy
= Epitaxy after alkali ion irradiation
and annealing in air or oxygen
Our Goal
Doping -quartz with photoactive elements via ion implantation.
Can we achieve full epitaxy & high luminescence efficiency?
Experiments
Na & Rb ion implantation & RBS-channeling: Defects in SiO2, Rb profiles
Elastic Recoil Detection Analysis (ERDA): Na profiles,16O  18O exchange
Atomic Force Microscopy (AFM): Surface structure
Cathodoluminescence (CL): Optical properties
RBS-Channeling
undamaged
sample ?
Angular scan
virgin sample
amorphous
Channeling cannot distinguish !!
polycrystalline
textured
Dynamic
epitaxy
Depth profiles: Time-of-flight ERDA
Start/Stop Detector
= Time marker
Field-free reg. -2.2 kV
C - 4.4 kV
Electron mirror -6.6 kV
Secondary electrons
5-50 MeV
recoil atom
Channel plate
chevron pair
Anode 0 V
500 ps
20 mV
Busch et al., NIM 171 (1980) 71
TOF-ERDA: 2 time markers T1 and T2
measure flight time t & velocity v = L/t.
Si detector measures recoil energy
E = M2v2/2. Deduce M2 from E and v.
TOF-ERDA is able to scan the full mass
range of target isotopes in a single run.
J. Jokinen, et al., NIM B 119 (1996) 533
2. Chemical epitaxy: Rb
2500
Counts
2000
virgin
18
virgin in O
random virgin
as implanted
16
O
1500
923 K
1023 K
1073 K
1098 K
1133 K
(a)
Rb-ions implanted
(175 keV, 2.5x1016/cm2, 100 K).
Annealed in 18O2-gas
S. Gasiorek, et al, JAP 95 (2004)
1000
18
O
500
100
Si
400
500
600
700
800
Energy (keV)
fV (%)
300
60
40
1.2
20
(b)
0.4
0.0
0
500
1000
1500
15
2000
2500
2
Depth (10 at./cm )
0.06
as implanted
773 K
843 K
923 K
973 K
a/c interface
0.04
0.02
(c)
0.00
0
500
1000
1500
15
2000
2
Depth (10 at./cm )
2500
(a)
Amorphous
0
Retained Rb fraction (%)
as implanted
923 K
1023 K
1073 K
1098 K
1123 K
1133 K
0.8
Oxygen content (%)
Normalized damage
as-impl.
80
0
Rb concentration
TX
Rb
fraction
100
TD
80
as-impl.
60
40
20
Retained
(b)
0
Rb
100
16O
80

18
O fraction
O fraction 18
O
16
20
18O
(c)
 16O

0
0
200
400
600
800
Temperature (K)
1000
1200
Chemical epitaxy: Fluence dependence
Na: Fixed annealing temp. 1173 K;
Rb: Fixed annealing temp. 1123 K;
RBS Channeling
Counts
3000
18
2000
virgin O2
random virgin
14
2
1.0x10 Na/cm
15
2
1.0x10 Na/cm
16
2
1.0x10 Na/cm
16
2
2.5x10 Na/cm
17
2
1.0x10 Na/cm
16
O
1000
Si
18
O
0
250
300
350
400
450
Energy (keV)
500
550
Energy (keV)
Results:
Thickness of damaged layer increases with ion fluence
Need critical ion fluence to achieve epitaxy:  21016/cm2
Very little damage left in SiO2 after epitaxy
Chemical epitaxy: Oxygen diffusion (Na)
50
40
923 K
(a)
14
20
18O
concentration profiles measured
by means of TOF-ERDA for Na-doped
-quartz annealed in 18O2 for 1 h
at 923 K (a) and 1123 K (b).
10
40
The insert shows the total 18O
content integrated up to the a/c
interface for different fluences
40
1123 K
(b)
(c)
O content (%)
0
30
18
O concentration (at.%)
30
18
2
1.0x10 /cm
15
2
1.0x10 /cm
16
2
1.0x10 /cm
16
2
5.0x10 /cm
17
2
1.0x10 /cm
20
30
20
10
0
923 K
1123 K
0
20
40
60
80
15
10
0
-50
100
2
Fluence (10 Na/cm )
0
50
100
150
Depth (nm)
200
250
Oxygen exchange with 18O
annealing gas is very effective:
for 5x1016 alkali-ions/cm2,
15-30 % of the oxygen content
in the a-SiO2 is replaced by 18O.
Ge and Rb diffuse in amorphous zone ERDA & RBS.
Chemicalenhanced
epitaxy:
Rb out-diffusion
by double-ion
presence of Geimplantation
ERDA & RBS.
For Ge-fluences  1015/cm2, full epitaxy of SiO2 layer;
75% of implanted Ge substitute Si in quartz matrix RBS-CGe/Rb
.
3000
Si + Cs as impl.
Si as impl.
1000
O
Cs
2000
virgin
875 C
400
Si
1000
o
0
200
Virgin
Random
16
2
10 Ge/cm (as-impl.)
16
2
10 Ge/cm (ann.)
16
2
Rb + 10 Ge/cm (as-impl.)
14
2
Rb + 10 Ge/cm (ann.)
15
2
Rb + 10 Ge/cm (ann.)
16
2
Rb + 10 Ge/cm (ann.)
3000
2000
600
800
Energy (keV)
Counts
Normalized Yield
Si/Cs
4000
0
250
800
300
350
Ge
3000
Normalized Yield
Xe/Cs
600
400
450
15
500
200 Rb + 10 Ge/cm (ann.)
Channeled Ge
Random
400
Xe + Cs as impl.
Xe as impl.
Rb
200
0
1000
600
Xe
virgin
850 C
400
600
600
Energy (keV)
700
800
0
o
0
200
75% Ge
on Si sites
Rb
100
2000
550
2
800
700
800
Energy (keV)
900
1000
Ge nanocrystals
XTEM picture of SiO2/Si bilayer
irradiated with Ge ions and annealed
TEM picture of Ge nanocrystals
after Implantation in SiC
J. M. J. Lopes, et al.,
Appl. Phys. Lett. 86 (2005)
Chemical epitaxy after alkali implantation: Scenario
SiO2 consists of
fully connected
SiO4 tetraeders:
O3Si-O-SiO3 
no topological
freedom!
Alkali ions are
network modifiers,
which are bound to
O & weaken Si-O
bond.
Arnold + Mazzoldi,
Marians + Hobbs
Possible Scenario:
O3Si–O†SiO3 + 2A + 18O
 O3Si–O–A + A–18O–SiO3
 O3Si–18O–SiO3 + A2O
Dynamic epitaxy (Ba, Ge)
Counts (x100)
30
Ba(a)
Random
O
920 K
20
1020 K
RT
Ba (x10)
1095 K
Si
120-keV Ba+ ions, fluence = 1 x 1015/cm2,
sample temperature = 300 - 1170 K.
The amorphized quartz layer stays damaged
up to 1170 K near surface, thickness of the
amorphous layer decreases for increasing
sample temperature.
S. Dhar, et al., J. Appl. Phys. 85 (1999)
1120 K
10
1170 K
Virgin
P. K. Sahoo, et al., J. Appl. Phys. 96 (2004)
0
300
450
600
120-keV Ge+ ions, fluence = 7x1014 ions/cm2
750
Normalized Damage
(b)
1.0
RT
870 K
1070 K
1095 K
1120 K
1170 K
0.8
0.6
0.4
0.2
0.0
0
400
800
15
1200
2
Depth (10 at./cm )
Nearly full epitaxy!
1600
(a)
Random
3
Normalized Yield (x 10 )
Energy (keV)
3
Nearly no epitaxy!
Ge
O
2
923 K
RT
1023 K
1073 K
1123 K
1
1173 K
Virgin
1223 K
0
200
300
400
500
Energy (keV)
Si
600
3. Luminescence in Quartz & Silica
Luminescence mechanisms:
Excitation via electrons or UV?
Quantum efficiency?
Non-radiative transitions?
Temperature dependence?
Luminescent defect structures:
Atomistic defects, nanoparticles?
If nanoparticles: elements or oxides?
crystalline or amorphous?
embedded in quartz or silica?
at interfaces?
New:
.
Comparison silica – quartz
Implant different ions
Sytematics of annealing conditions
Cathodoluminescence (CL)
e-gun
e -gun(CL)
InGaAs-diode
/ photomultiplier
Photomultiplier
CCD-camera
CCD camera
exit slit
mirror
HV - chamber
closed cycle
Closed cycle Sampl
He cryostat e
grating
entrance slit
achromate
aperture
long pass filter
band pass filter
focus lense
mirror
spectrograph
Spectrograph
laser(PL)
Laser
(UV-) mirror
chopper
 Wavelength range: 190 – 1700 nm
 Temperature range: 12 K – 300 K
 Maximal  resolution: 5 pm (photomultiplier), 40 pm (CCD)
 Electron gun energy range: 100 eV – 5 keV (depth  100 nm)
Chemical epitaxy: Na & Rb temperature dependence
CL @ 300 K
20
Integrated CL Intensity (arb. unit)
Virgin -quartz
Amorphous -quartz
(800 keV Ba)
Grown SiO2 on Si
(a)
Intensity (arb. unit)
Fused quartz
(b)
843 K
1023 K
1173 K
Rb
(c)
873 K
973 K
1123 K
Na
2.40 eV
2.79 eV
4.30 eV
15
Rb
10
(a)
5 as-impl.
0
80
TD = 860 K
60
40
Rb
20
3.25 eV
3.65 eV
(b)
TX = 1060 K
as-impl.
0
20
TX = 930 K
15
(c)
Na
10
5
as-impl.
TD = 830 K
0
1,5
2,0
2,5
3,0
3,5
4,0
Energy (eV)
4,5
5,0
0
100 800
900
1000
1100
1200
Temperature (K)
J. Keinonen, et al., Appl. Phys. Lett. 88 (2006)
Chemical epitaxy: Na fluence dependence
S. Gasiorek, et al. (2006, 2008)
14
Intensity (arb. unit)
2
1.0x10 Na/cm
16
2
1.0x10 Na/cm
16
2
5.0x10 Na/cm
16
2
7.5x10 Na/cm
17
2
1.0x10 Na/cm
16
2
5.0x10 Na/cm as-impl.
(a)
2
3
4
(a)
14
3
(b)
2.40 eV
2.79 eV
3.25 eV
3.65 eV
4.30 eV
CL @ RT
-2
10
-3
10
-4
10
-5
10
0
2
4
6
8
16
10
2
Na-ion fluence (10 /cm )
Integrated CL intensity (arb. unit)
Integrated CL intensity (arb. unit)
Energy (eV)
-1
2
1.0x10 Na/cm
16
2
1.0x10 Na/cm
16
2
5.0x10 Na/cm
16
2
7.5x10 Na/cm
17
2
1.0x10 Na/cm
16
2
5.0x10 Na/cm as-impl.
2
5
10
10 K
Intensity (arb. unit)
CL @ 300 K
4
Energy (eV)
5
0.3
(b) CL @ 10 K
0.2
2.90 eV
3.25 eV
0.1
0.0
0
2
4
6
8
16
10
2
Na-ion fluence (10 /cm )
Chemical epitaxy: Rb & Na fluence dependence
Na
Annealing @ 1123 K in
(a)
14
3
4
Energy (eV)
(b) CL @ 10 K
0.2
2.90 eV
3.25 eV
0.1
0
2
4
Intensity (arb. unit)
15
6
8
16
10
2
Na-ion fluence (10 /cm )
2
1.0x10 Rb/cm
16
2
1.0x10 Rb/cm
16
2
1.75x10 Rb/cm
16
2
3.5x10 Rb/cm
16
2
5.0x10 Rb/cm
2
0.3
Rb
CL @ 10 K
(a) 10 K
5
Integrated CL Intensity (arb. unit)
Intensity (arb. unit)
Integrated CL intensity (arb. unit)
2
1.0x10 Na/cm
16
2
1.0x10 Na/cm
16
2
5.0x10 Na/cm
16
2
7.5x10 Na/cm
17
2
1.0x10 Na/cm
16
2
5.0x10 Na/cm as-impl.
2
0.0
18O -gas,
2
3
4
Energy (eV)
5
300
(b)
200
2.95 eV
3.25 eV
4.9 eV
100
0
0
1
2
3 16 4 2
Rb fluence (10 /cm )
5
6
Chemical epitaxy: Rb+Ge; fluence dependence
Integrated Intensity (arb. unit)
Intensity (arb. unit)
0.6
(a)
RT
0.5
0.4
0.3
Results:
virgin
Rb+Ge (As implanted)
16
2
1x 10 Ge/cm
14
2
Rb + 1x 10 Ge/cm
15
2
Rb + 1x 10 Ge/cm
16
2
Rb + 1x 10 Ge/cm
0.2
0.1
0.0
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
Green (2.4 eV)
Blue (2.72 eV)
Blue-Violet (2.95 eV)
Violet-1 (3.25 eV)
Violet-2 (3.53 eV)
UV (4.3 eV)
2
10
1
Photon energy (eV)
(b)
10
CL @ 300 K
1) Intensities of intrinsic bands
(2.40 & 2.79 eV) are nearly
independent of Ge-fluence.
2) Intensities of violet bands
(2.95, 3.25 & 3.53 eV) rise
strongly with Ge-fluence.
By double Rb/Ge
irradiation, we have
found a road to
achieve high CL output
and full epitaxy!!
Ge-asimpl.
0
10
Rb/Ge-asimpl.
1
10
100
14
2
Ge-Fluence (10 ions/cm )
P. K. Sahoo, et al., NIM B240 (2005);
Appl. Phys. Lett. 87 (2005)
CL in quartz: Quantum efficiency @ RT
100
Tann = 1120 K
45
Ge+Rb-chem
Ge-chem
Rb+Ge - chem
40
CL eff. [arb. unit]
15
2
Intensity/(10 ions/cm )
50
Ge - dyn
35
30
25
Ge - chem
20
15
Na - chem
Ba - dyn
Virgin
10
Rb - chem
Ge-dyn
10
Na-chem
Ba-dyn
Rb-chem
1
Tann = 1120 K
5
Violet band
0
2
3
4
Energy (eV)
5
0.1
0
20
40
60
80
100
120
Atomic Mass (amu)
Ge-dyn or Ge-chem give high CL output, but no epitaxy.
Na-chem, Rb-chem & Ba-dyn give epitaxy, but low CL.
Only Ge+Rb-chem provides high CL intensity & full SPEG.
Sahoo, Gasiorek, Dhar, Lieb, NIM B 249 (2006)
140
Intensity (arb. unit)
virgin -quartz
amorphous -quartz (800 keV Ba)
grown SiO2 on Si
4. Interpreting CL data
RT
Intrinsic Bands
fused quartz
not related to the way a-SiO2 is
prepared: ion implantation, vapor
deposition, chemical reaction
Intrinsic bands of virgin quartz
e-beam irradiation --------
Intrinsic bands of silica
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Energy (eV)
Tann = 1120 K
45
15
2
Intensity/(10 ions/cm )
50
Rb+Ge - chem
40
RT
K. Stevens-Kalceff, JAP97 (2005);
L.Skuja, et al, PSS(c) 2 (2005);
J. Keinonen, et al., APL 88 (2006)
Ge - dyn
35
Amorphized quartz
a-SiO2 grown on Si
Fused quartz (a-SiO2)
30
25
Ge - chem
20
15
Ion-specific bands
Na - chem
Ba - dyn
Virgin
10
Rb - chem
5
0
2
3
Energy (eV)
4
5
Dynamic or chemical epitaxy
@ 1120 K:
Ge-dyn, Ba-dyn;
Na-, Rb-, Ge-chem;
Rb+Ge-chem
Classification of CL bands @ RT
Ba, Na, Rb, Cs, Ge
Ion species; E (eV)
 (nm)
Identification
Ba: 2.00(2)
617, red
Non-bridging oxyg.-hole: ≡Si–O•
All: 2.40(2)
514, green
Oxygen-vacancy interstitial pairs
[Intr]
Rb/Ge, Ge: 2.72(2)
Na, Rb, Ba: 2.79(4)
454, blue
442, blue
ODC center: ≡Si–Si≡,
E´-center: ≡Si•Si≡, ≡Si•
[Intr]
Ge, Rb/Ge: 2.95(2)
418, violet
Ge- and/or Rb-related defect?
All, Rb/Ge: 3.25(2)
380, violet
Ge-, alkali-related defect?
Ba: 3.40(5)
363, violet
Ba-related defects
Rb/Ge: 3.53(3)
350, violet
Ge- and/or Rb-related defect
Alkali: 3.65(4)
338, violet
Alkali-related defect: ≡Si-O-A
All, Rb/Ge: 4.30(2)
287, UV
ODC center, E´-center
Ref.
[Intr]
[Intr] Stevens-Kalceff, et al., PR B52 (1995); PR B57 (1998); PRL 88 (2000)
The 3.25 & 3.65 eV CL bands
How do intensities depend on the annealing conditions?
Integrated CL Intensity (arb. unit)
 = 2.5x1016/cm2; TCL = 300 K
20
15
Na
Na
10
(a)
TX = 930 K
3.25 eV
3.65 eV
TX930 K
has recrystallized
0 TD830 K
80
(b)
TD = 860 K
Rb
Rb
40
20
TD = 860 K
TX=1060K
as-impl.
TX = 1060 K
0
0
100 800
ions have outdiffused
TX: 90% of amorphized zone
5 as-impl. TD = 830 K
60
TD: 90% of implanted alkali
900
1000
Temperature (K)
1100
1200
J. Keinonen et al.,
APL 88 (2006)
Atomistic Defects
Defect-free
Quartz
Self-Trapped Exciton
(STE)
Ge-oxygen-deficient
center (GODC)
Non-bridging
oxygen hole
(NBOHC+A)
E´ center
Figure taken from Lieb & Keinonen, Contemp. Phys. 47 (2006).
A scenario for the 3.25-eV CL band
Si implantation in silicon-rich silica
?
?
F. Flores Gracia, et al., Superficies y Vacío 18 (2005) 7
Status Spring 2009
Epitaxy:
Dynamic: Ne, Ba ☺
Chemical: Na, Rb, Cs ☺
Laser:
Luminescence:
Intrinsic bands
Ion-specific band
Correlations between 2.95 & 3.25 eV bands
Ge partially
Li partially
Ba, Rb, Cs partially
Chemical epitaxy + strong luminescence: Ge+Rb
Full recristallization for alkali ions & high
CL intensity through Ge;
Ge predominantly on Si-sites
Further investigations:
Atomistic defects vs. nanoparticles?
T-dependent & time-differential CL
Laser epitaxy, PL & absorption spektroscopy
TEM, EPR, NMR, RAMAN, post-irradiation, …
Theoretical modeling
K. P. Lieb & J. Keinonen, Cont. Phys. 47 (2006) 305; K. P. Lieb et al.,
Physica B 389 (2007); Rad. Eff. Def. Matter 162 (2007) 575;
J. Keinonen, et al., in “Silicon Nanophysics” (World Scientific, 2008)
5. Outlook: Time differential CL (Rb/Ge)
Time-differential CL with pulsed electron beam;
Time resolution 0.8 s FWHM
Time constants:
2.95 eV band:  = 5.7 s
3.25 eV band:  = 4.5 s
CL Intensity (arb. unit)
1
 = 5.7 s (3.25 eV)
Skuja (1986,1998)
0.1
0.01
 = 4.5 s (2.95 eV)
0
10
20
30
Time (s)
40
50
3-Level System.
Ge-related ODC centers have
luminescence lifetimes of
  110 s for T1  S0 transition,
and   6 ns for S1  S0 emission.
We may attribute the observed
lifetimes to T1  S0 transition.
P. K. Sahoo, et al., Appl. Phys. Lett. 87 (2005)
Laser epitaxy (Cs)
2500
Counts
2000
virgin
random virgin
as-impl.
2
4.0 J/cm
2
4.4 J/cm
2
4.7 J/cm
O
1500
Cs
1000
Si
500
Retained Cs fraction (%)
250-keV Cs ions, fluence = 2.8x1016 /cm2;
SIEMENS XP2020 excimer laser:  = 308 nm, 300 K in air;
5×5 mm² laser spot: 3.2 - 4.7 J/cm²; 20 pulses at rate of 8 Hz
110
100
90
80
70
60
50
40
0
300
400
500
Energy (keV)
700
800
0
1
2
3
4
2
Energy density (J/cm )
No full epitaxy achieved
Cs diffuses to surface and starts evaporating above 4.4 J/cm2
S. Gasiorek, et al., Appl.. Surf. Sci. 247 (2005) 396
5
Laser epitaxy (Cs)
Corrected intensity [a. u]
25
Blue
(a)
pristine
as-impl.
2
4.7 J/cm
2
4.5 J/cm
2
4.4 J/cm
2
4.0 J/cm
2
3.2 J/cm
20
15
Blue-Violet
10
Violet
Green
UV
5
1,5
2,0
2,5
3,0
3,5
4,0
4,5
5,0
5,5
Integrated intensity [a. u]
Energy
(eV) (eV)
Photon
energy
100
10
1
2.42 eV (Green)
2.79 eV (Blue)
3.25 eV (Blue-Violet)
3.65 eV (Violet)
4.30 eV (UV)
CL spectrum:
Intrinsic lines
@ 2.42, 2.79 & 4.30 eV
Ion-specific bands
@ 3.25 & 3.65 eV (Cs)
0,01 as-impl.
3,6
Siemens XP2020 XeCl
excimer laser:
Pulse duration 55 ns,
Wavelength 308 nm,
Power 3.2 - 4.7 J/cm²
20 pulses at rate of 8 Hz.
(b)
0,1
-0,5 0,0 3,2
250 keV Cs-ions implanted
Fluence  = 2.8×1016/ cm2
Range RpCs  110 nm
4,0
4,4
2
Energy density
) 2)
Laser
power(J/cm
(J/cm
4,8
S. Gasiorek, et al.,
Appl. Surf. Sci. 252 (2006)
Surface Structures (Na)
Na+-ions (5.01016/cm2; 50 keV). Annealed for 1 h in 18O2
at 973 K (a); 1023 K (b); 1073 K (c), and 1123 K (d)
a
b
40 nm
20 nm
0.0
4.0
8.0
m
c
d
40 nm
10 nm
0.0
4.0
8.0
m
0.0
4.0
8.0
m
0.0
4.0
8.0
m
Surface Structures: Spider Net (Rb)
AFM images of -quartz irradiated with Rb+-ions
(175-keV, 21016 ions/cm2). Annealed at 1173 K in 50-mbar 18O2
K.P. Lieb, et al., SPIE 7142 (2008)
Polymorphs of Quartz
Coesite
monoclinic
ß (high) Quartz
hexagonal,
stable > 573ºC
ß-Tridimyte
hexagonal
870-1470ºC
 (low) Quartz
trigonal
Non-irradiated Si-nc in silica
Molecular Dynamics simulations
Si-nc in silica destroyed by protons
J. Keinonen, F. Djurabekova, K. Nordlund &
K. P. Lieb, in Silicon Nanophotonics (2008)
Collision cascade of 2-keV Si-ion in quartz
0.4 ps after impact from the left
Si-nc in silica irradiated with
1-keV Si ions at an energy
of 5 eV/Si-atom in nc, where
amorphization takes place
Quartz everywhere
Thank you!
Chemical epitaxy: Rb/Ge
ERDA: Rb and Ge profiles
RBS-C: Damage profile, Ge
4000
Virgin
Random
16
2
10 Ge/cm (as-impl.)
16
2
10 Ge/cm (ann.)
16
2
Rb + 10 Ge/cm (as-impl.)
14
2
Rb + 10 Ge/cm (ann.)
15
2
Rb + 10 Ge/cm (ann.)
16
2
Rb + 10 Ge/cm (ann.)
3000
O
2000
Si
Counts
1000
0
250
800
300
350
Ge
600
400
450
15
500
200 Rb + 10 Ge/cm (ann.)
Channeled Ge
Random
75% Ge
on Si sites
Rb
100
400
550
2
Rb
200
0
600
700
800
0
600
700
800
900
1000
Energy (keV)
1) Ge and Rb diffuse in amorphous zone ERDA & RBS.
2) Rb out-diffusion enhanced by presence of Ge ERDA & RBS.
3) For Ge-fluences  1015/cm2, epitaxy of SiO2 layer;
75% of implanted Ge substitute Si in quartz matrix RBS-C.
Chemical epitaxy: Rb (CL)
For comparison:
Intrinsic bands of quartz and silica
2,0
1,5
virgin -quartz
grown SiO2 on Si
1,0
fused quartz
(a)
2.51016/cm2 Rb
ions implanted.
Chemical epitaxy in air
(1h @ 843 – 1173 K)
Chemical epitaxy in 18O2-gas
(1h @ 843 – 1173 K)
Intensity (arb. unit)
0,5
0,0
2,0
1,5
1,0
0,5
0,0
2,0
1,5
1,0
0,5
S. Gasiorek, et al.,
J. Non-Cryst. Solids 252 (2006)
0,0
1,5
virgin
as-impl.
843 K
923 K
1023 K
1088 K
1173 K
843 K
(c)
1173 K
843 K
923 K
1023 K
1133 K
1173 K
2,0
(b)
843 K
2,5
3,0
3,5
Energy (eV)
4,0
4,5
5,0
RBS-Channeling: Amorphous surface layer
-beam
1 MeV -beam
beam diverges in amorphous layer
undamaged
sample ?
virgin sample
Defects II
P. V. Shusko, et al., J. Phys., Cond. Matter 17 (2005)
1 keV Si-Implantation
 8 nm SiO2/Si:
Nucleation, Growth
& Decomposition
Snapshots of KMC simulations and cross
section of phase separation in 8-nmthick SiO2 on Si <001> during annealing. The simulations start from
1 keV Si profiles for fluences of (a)
3x1015 cm-2, (b) 5x1015 cm-2, and (c)
1x1016 cm-2, respectively (TRIDYN).
Two regimes were identified, nucleation
& growth (a) and spinodal decomposition (b,c). Additionally, percolation is observed at the highest
fluence (c). Atoms are colored
according to their coordination.
The 15 nm scale only applies for
the lower-right corner.
Müller, Heinig, and Möller,
Appl. Phys. Lett. 81 (2002) 3049
1-keV Si-Implantation
 8 nm SiO2/Si
Depth profiles of 1-keV Si+  SiO2
Width of the denuded zone (a)
and mean nanocluster diameter &
density (b) during annealing for
both regimes, nucleation and
spinodal decomposition
Müller, Heinig, and Möller,
Appl. Phys. Lett. 81 (2002) 3049